This disclosure is generally directed to layered imaging members, photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to rigid or drum photoreceptors, and to multilayered flexible, belt imaging members, or devices comprised of an optional supporting medium like a substrate, a photogenerating layer, a charge transport layer, and a polymer coating layer, an optional adhesive layer, and an optional hole blocking or undercoat layer. The photoreceptors illustrated herein, in embodiments, have excellent wear resistance; extended lifetimes; provide for the elimination or minimization of imaging member scratches on the surface layer or layers of the member, and which scratches can result in undesirable print failures where, for example, the scratches are visible on the final prints generated; permit excellent electrical properties; minimum cycle up after extended electrical cycling, such as 10,000 simulated cycles; increased resistance to running deletion, know as LCM; and mechanical robustness. Additionally, in embodiments the imaging or photoconductive members disclosed herein possess excellent, and in a number of instances low Vr (residual potential), and the substantial prevention of Vr cycle up when appropriate; high sensitivity, and desirable toner cleanability.
Also included within the scope of the present disclosure are methods of imaging and printing with the photoreceptor devices illustrated herein. These methods generally involve the formation of an electrostatic latent image on the imaging member, followed by developing the image with a toner composition comprised, for example, of thermoplastic resin, colorant, such as pigment, charge additive, and surface additive, reference U.S. Pat. Nos. 4,560,635; 4,298,697 and 4,338,390, the disclosures of which are totally incorporated herein by reference, subsequently transferring the image to a suitable substrate, and permanently affixing the image thereto. In those environments wherein the device is to be used in a printing mode, the imaging method involves the same operation with the exception that exposure can be accomplished with a laser device or image bar. More specifically, the photoreceptors disclosed herein can be selected for the Xerox Corporation iGEN3® and Nuvera® machines that generate with some versions over 100 copies per minute. Processes of imaging, especially xerographic imaging and printing, including digital, and/or color printing, are thus encompassed by the present disclosure. The imaging or photoconductive members disclosed are in embodiments sensitive in the wavelength region of, for example, from about 400 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source.
There is an intense competitive pressure to improve the functional performance of xerographic photoreceptors. For example, it is desirable to reduce Lateral Charge Migration (LCM) and improve mechanical strength. Also, it is desirable to minimize changes in its electrical characteristics during prolonged electrical cycling. The concentration of the charge transport molecules at the surface of the charge transport layer (CTL) is a known factor in the severity of lateral charge migration (LCM) caused by oxidation of the transport molecule. Also, the concentration of the charge transport molecule in the bulk CTL is a known factor in the formation of printable stress cracks in PR devices. The lower the concentration of the transport molecule at the surface, the lower the severity of LCM. Also, the lower the concentration of the transport molecule in the bulk, the less susceptible the device will be to printable cracks. The presently disclosed embodiments relate to an imaging or photoconductive member having a charge transport layer in which a charge transport molecule (CTM) concentration gradient, wherein the concentration of the CTM is lower at the surface of the CTL than it is toward the substrate side of the CTL.